Your Dementia Risk May Increase if Your Mother Has Alzheimer's

Key Takeaways

• Among healthy adults, those who had with a mother with Alzheimer's disease were likely to have a higher amount of amyloid plaques in the brain than those who had a father with Alzheimer's, according to a new study.
• Amyloid plaques are clumps of misfolded proteins that have been linked to cognitive impairment.
• Researchers can measure amyloid plaques in healthy people to predict whether they're at risk of dementia.

A new study suggests that whether and when your parents develop Alzheimer's disease can impact your own brain health later in life.

Researchers examined data from more than 4,400 adults without any history of cognitive impairment, including questionnaires about family dementia history and brain scans. When an individual's mother, or both parents, had Alzheimer's disease, the person had significantly higher levels of so-called amyloid plaque deposits in their brain that can hasten cognitive decline, compared with participants who had only a father with Alzheimer's, according to study results published in JAMA Neurology .

Amyloid plaques are clumps of misfolded protein in the brain that have long been associated with cognitive impairment.

"Our results show that genetic risk captured by family history of dementia affected amyloid-beta protein accumulation even in asymptomatic older adults," says the senior study author, Hyun-Sik Yang, MD , an assistant professor of neurology at Harvard Medical School and Brigham and Women's Hospital in Boston.

"Interestingly, this association was stronger with maternal history," Dr. Yang says.

Risk Tied to Mothers With Alzheimer's Disease

People had a higher risk of amyloid accumulation no matter what age their mother was when she developed Alzheimer's disease, the study found. On the paternal side, participants' dementia risk only went up when their fathers developed Alzheimer's disease earlier in life - before age 65.

Because Alzheimer's disease can only be definitively diagnosed with an autopsy of the brain, scientists look for evidence of amyloid plaque accumulation in the brain as one way to identify this as a potential diagnosis when people experience cognitive decline. Amyloid plaques can start to build up in the brain long before people have any symptoms of Alzheimer's disease.

For the study, researchers relied on participants to report on any memory loss or cognitive impairment experienced by their parents. Just 10 percent of parents who experienced memory or cognitive issues according to the study participants had an autopsy-confirmed case of Alzheimer's disease.

The Study Had Some Limitations

One limitation of the study is that participants were typically in their seventies, meaning their parents were likely born in the 1920s, the study notes. Men born back then had a life expectancy of about 62 years, compared with 69 years for women, and may not have lived long enough to develop late-onset cognitive impairment, according to the study.

Beyond this, maternal Alzheimer's disease was linked to just 3 percent more amyloid plaques in people's brains, and even though this is statistically meaningful, it's not yet clear how big an impact this difference would have in people's day-to-day lives, wrote Dena Dubal, MD, PhD , a neurology professor at the Weill Institute of Neurosciences at the University of California in San Francisco, in an editorial accompanying the study.

Even so, the findings suggest some clear-cut things people may want to do when they know their mother had Alzheimer's disease, Dr. Dubal wrote in the editorial.

"For example, a maternal history of Alzheimer's disease may influence genetic risk assessment in individuals with a family history of Alzheimer's disease, which could, in turn, impact motivations to robustly alter lifestyle behaviors aimed at mitigating disease risk," Dubal wrote.

Yang routinely tells patients that lifestyle choices can make a big difference in keeping their brain healthy as they age.

"As a neurologist, I advise my patients to eat a heart-healthy diet such as a Mediterranean diet ; exercise regularly, aiming for 30 minutes, five days a week, of moderate intensity exercise; have good social interactions with friends and family; and optimally manage cardiovascular risk factors such as blood pressure , blood sugar, and cholesterol to keep their brain healthy," Yang says.

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Sources

1. Seto M et al. Parental History of Memory Impairment and β-Amyloid in Cognitively Unimpaired Older Adults. JAMA Neurology . June 17, 2024.
2. Dubal D et al. β-Amyloid in Cognitively Unimpaired Individuals - Blame Mom? JAMA Neurology . June 17, 2024.